For various research and experiments for geoscience and mineral resources, there is a need to collect samples. To this end, various types of sample collecting apparatuses and coring apparatuses have been proposed.
Describing in detail, since marine sediments have well preserved information in respect to a global environment change over a long period of time, the marine sediments have been utilized as palaeoecological research data and important research data for tracing and developing seabed mineral resources (manganese nodules, phosphoanhydrite, marine sand, and the like) and energy sources (oil, gas, gas hydrate, and the like).
Further, the marine sediments provide important research data about seabed geologic storage, and the like. Such information may be used to reduce pollution or dioxide carbon at a coastal area which has a direct relationship on human activities.
As described above, collecting samples of marine sediments is one process essential for research and development. To this end, various types of apparatuses for collecting marine sediments have been proposed.
There is a coring apparatus having the core filled with the marine sediments when the core is inserted into the seabed. The core is disposed in an external tube having a pipe form, such as a piston corer, a gravity corer, a multi corer, and the like, in the apparatus for collecting marine sediments.
However, in prior art devices, the marine sediments filled in the core are excessively disturbed or flow down from the core. As a result, the marine sediments are lost during pulling up of the coring apparatus to a ship after the coring apparatus performs the coring operation. Therefore, the coring operation itself becomes unproductive.
In particular, when the coring operation is performed in soft ground, the loss of the marine sediments frequently occurs in the core and, as a result, data may not be obtained through the coring operation.
That is, the marine sediments need to be retained in the core intact without the loss of the marine sediments from the core and without disturbance, such as the mixing of the marine sediments. In such fashion, highly reliable data may be obtained through the samples of the marine sediments.
In order to prevent the samples in the core from being lost and disturbed during the pulling up of the coring apparatus, as disclosed in Korean Patent No. 1029693, the coring apparatus in which a top portion of the core can be sealed.
However, the related art as described above is a technology of moving upwardly the piston disposed in the core by a pressure generated during the process of filling the marine sediments in the core. This occurs when the external pipe and the core of the coring apparatus are inserted into the seabed and a packing is disposed at the outside of the piston to prevent a gap from being formed between the packing and the core.
Therefore, when the packing is removed or a pressure is applied to the piston while the piston moves upwardly, the piston does not move smoothly, and the operation of the piston is not as efficient.